大展弦比机翼非线性颤振特性研究

Research on nonlinearity flutter characteristics of a high-aspect-ratio wing

为了研究大展弦比机翼水平弯曲模态参与耦合时的颤振特性,首先用考虑几何非线性的颤振分析方法研究了某大展弦比机翼的颤振特性,建立了大展弦比机翼非线性颤振分析的简化模型,即盒段模型;然后通过组合不同的水平弯曲频率、扭转频率形成不同的接近模式,系统分析了不同接近模式对盒段模型非线性动力学特性的影响规律,提出了水平弯曲频率和扭转频率发生模态交换的存在条件。在此基础上通过对盒段模型进行非线性颤振分析发现:水平一弯模态参与耦合降低了机翼传统模式的线性颤振速度,增大水平一弯的频率有助于该类颤振速度的提高;在水平一弯频率和扭转频率逐步接近时,会导致机翼颤振速度显著下降,且颤振类型会由水平一弯和垂直弯曲耦合的颤振转化为水平一弯和扭转耦合的颤振。

To study the coupled horizontal-bending flutter characteristics of a high-aspect-ratio wing, the flutter characteristics of the high-aspect-ratio wing with geometric nonlinearity are illustrated. The wing model is represented by a simplified slender box section model. The close mode on the influence law of nonlinear dynamics is implemented through the combination of different horizontal bending frequency and torsion frequency. The existence condition of the horizontal bending frequency and torsion frequency occurring modal exchange is proposed. Numerical results obtained indicate that the flutter speed is decreased when the first horizontal bending mode involved. Thus, the increasing of the natural frequency of the first horizontal bending mode is helpful to improve the flutter speed. Moreover, on condition that the first horizontal bending frequency and torsion frequency approaches gradually will lead to wing flutter speed descends significantly and the flutter pattern can be changed from the interacting of the first horizontal bending mode with vertical bending mode to the interacting of the first horizontal bending mode with the torsional mode.